A laminated ceramic capacitor is an electronic component that is used in the circuits of a wide variety of electronic devices, and downsizing of a laminated ceramic capacitor is necessary as such an electronic device is downsized.
Such a type of the laminated ceramic capacitor is formed by laminating dielectric layers interposed by internal electrodes, and sintering the laminate. For achieving downsizing of the laminated ceramic capacitor without causing reduction in its capacity, it is necessary to thin the dielectric layer.
However, when the dielectric layer is thinned, a high field voltage intensity is applied to the dielectric layer, so that a decrease in dielectric constant or a deterioration in temperature characteristics may be caused, or the insulation resistance may decrease as a result of long-time driving at a high temperature, to increase the possibility of occurrence of defective articles. This may result in deterioration in reliability.
Therefore, it is necessary to realize a dielectric ceramic having a large dielectric constant, excellent temperature characteristics and excellent reliability even if a high field voltage intensity is applied due to thinning of the dielectric layer.
In light of this, conventionally proposed is a dielectric ceramic having a composition containing a main ingredient composed of a perovskite-type compound represented by ABO3 (wherein A represents Ba and Ca, or Ba, Ca and Sr, and B represents Ti, or Ti and at least one of Zr and Hf), and an additive component containing Si, a predetermined rare earth element R and a predetermined metal element M, and having crystal grains and crystal grain boundaries occupying intervals between the crystal grains, wherein the additive component is not solid-solved in a region of 90% or more of the cross section for 85% or more in the number of the crystal grains, the main ingredient is present, and at least said Ba, said Ca, said Ti, said Si, said R and said M are contained in 85% or more of analysis points in the crystal grain boundaries (Patent document 1).
In the Patent document 1 composition containing (Ba, Ca)TiO3 as a main ingredient, and containing Si, a predetermined rare earth element R and a predetermined metal element M as accessory components, and making the accessory components be present in the crystal grain boundaries while they are only a little solid-solved with the main ingredient, a high temperature load life is ensured and thus reliability is improved.
Patent document 1: Japanese Unexamined Patent Publication No. 2004-224653